The present invention relates to a packing container of the type which is manufactured from a plastic-coated fibrous material and which has a sealing fin extending across the upper end wall of the container. The packing material is joined inside to inside in a sealed union and the packing material layers are so joined that, at least along a part of the sealing fin, a tearing strip is disposed in the sealing fin which comprises a pull-lug accessible from outside the container. The tearing strip is sealed to the inner plastic coating of the packing material.
The usual form of packing container for distribution of milk, fruit juice and other liquid foodstuffs is manufactured from a web of paper or cardboard, plastic-coated on both sides, this web being formed to a tube in that the longitudinal edges of the web are joined together in an overlap joint, whereafter the tube formed is filled with the intended contents and sealed transversely by means of repeated flattening and transverse sealing operations along zones located at right angles to the longitudinal direction of the tube at a distance from one another. The sealed-off portions of the tube can be separated subsequently by means of transverse cuts in the said sealing zones, whereafter a parallelepipedic shape can be imparted to the packing units formed, most frequently through pressure-forming and folding of the packing material along crease-lines provided beforehand. In the course of the folding and forming work, double-walled, triangular lugs are formed at four corners of the packing container which can be doubled against, and sealed to, the side or end walls respectively of the packing container.
A packing container of the type referred to here will have a longitudinal overlap joint, namely the joint which constitutes the longitudinal joint of tube, and the upper and lower end walls of the container will have transverse, finlike sealing joints in which the packing material is joined inside to inside. The transverse and longitudinal sealing joints cross each other at the upper and lower end surface of the packing container.
Generally, in packing containers of the type mentioned here, one of the triangular corner lugs is used as an emptying opening which is opened by putting up the triangular lug from its doubled position against the packing container, and by tearing or cutting off the sealing fin so that a connecting duct to the interior of the container is achieved.
Since certain inconveniences may be experienced in the tearing of the triangular corner lug along a prepared perforation line, and as a cutting off of the sealing fin presupposes the use of a tool, it has been proposed instead to solve the problem in such a manner that a tearing strip is inserted in the sealing fin from the tip of the triangular corner lug serving as a pouring opening up to, and past, the point of crossing between longitudinal and transverse joint, so that the tearing strip is accessible from the outside of the container. With the help of such a tearing strip the sealing joint in the sealing fin can thus be broken or cut up, so that a pouring opening is achieved.
This form of package opening with the help of a tearing strip, where the tearing strip is intended to tear through the seal produced in order to form an emptying opening, has been found, however, not to function to complete satisfaction. In the first place, the tearing strip often fails to cut directly into the sealing joint but instead cuts between the paper material and the plastic coating on either of the material layers. This exposes the raw fibre surface of the paper layer of the packing material so that the contents, on being poured out through the emptying openings, come into contact with the absorbent, exposed fibre surface which rapidly swells up and loses its rigidity. Other inconveniences are that, among other things, relatively great forces are needed for tearing up the sealing joint, and it happens not infrequently that the tearing strip rips asunder the paper layer on one side of the sealing fin, i.e., the tearing strip.